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Adjuvant-arthritic (AA) rats were medicated with dexamethasone to determine if this glucocorticoid suppressed the activity of interleukin-1 (IL-1) or the acute phase response. Dexamethasone (0.1 mg/kg, p.o.) administered daily for two weeks to AA rats, significantly (p less than or equal to 0.01) decreased high splenic IL-1 production (60% inhibition). Dexamethasone at a 0.5 mg/kg dose reduced AA rat splenic IL-1 production below normal (100% inhibition). In addition, dexamethasone significantly inhibited the AA rat acute phase response as measured by reduction of plasma C-reactive protein levels and enhancement of plasma albumin and iron levels. Following medication with 0.02, 0.1 or 0.5 mg/kg dexamethasone, high plasma C-reactive protein levels decreased by 33, 77 and 95% respectively, compared to untreated AA controls. Under the same dosing regimen of 0.02, 0.1 or 0.5 mg/kg dexamethasone, plasma albumin levels increased by 44, 128 and 239% respectively, while plasma iron levels rose by 19, 64 and 98% respectively, compared to AA controls. At the 0.02, 0.1 and 0.5 mg/kg doses dexamethasone also significantly reduced injected and noninjected paw swelling in AA rats. In view of the ability of dexamethasone to decrease IL-1 production and the acute phase response often associated with it, it is possible that part of the anti-inflammatory activity of dexamethasone may stem from inhibition of IL-1 formation in vivo.

Interleukin-1 (IL-1) activity and the acute phase response, as measured by plasma CRP and iron, were used to determine if the standard disease modifying antirheumatic drugs (DMARDs), gold, chloroquine and D-penicillamine had a common profile of activity in the adjuvant arthritic (AA) rat. All drugs were tested at a dose which significantly reduced noninjected paw swelling in AA rats. Inhibition of paw edema ranged from 37% for D-penicillamine (100 mg/kg) to 69% for auranofin (10 mg/kg). Two week medication of AA rats with gold sodium thiomalate (GST, 10 mg/kg, i.m.) or auranofin (10 mg/kg, p.o.) resulted in a significant decrease in splenic IL-1 activity, as measured in the standard lymphocyte activating factor (LAF) assay. The acute phase response, often associated with elevated IL-1 activity, was also significantly reduced following treatment of AA rats with 10 mg/kg of GST or auranofin (oral gold). Inhibition of the acute phase response by gold was determined by a significant reduction of plasma CRP levels (56-71% reduction) and enhancement of plasma iron levels (27-52% enhancement). In contrast to the effect of GST and auranofin on IL-1, CRP and iron, treatment with chloroquine (20, 30 and 35 mg/kg) and D-penicillamine (55 and 100 mg/kg) failed to reduce the acute phase response (as measured by plasma CRP and iron) or alter LAF activity from AA rat spleen cell supernatants. Based on its ability to reduce LAF activity in spleen cell supernatants and reduce the acute phase response, it is possible that the activity of gold in the AA rat may in part be due to its ability to inhibit IL-1 production in vivo. The inability of chloroquine and D-penicillamine to alter LAF activity and the acute phase response in AA rats does not preclude their possession of an immunoregulatory mechanism of action, but it does indicate that their mechanism of action in the AA rat probably differs from that of GST and auranofin.

The purpose of the study was to determine the temporal relationship between lymphocyte activating factor (LAF) activity and the acute-phase response, as measured by plasma fibronectin (Fn), C-reactive protein (CRP), and albumin levels in adjuvant arthritic rats. LAF activity as measured in the thymocyte costimulator assay, and plasma Fn, CRP, and albumin levels were measured during the acute (Day 3), intermediate (Day 10), and systemic (Day 17) phases of arthritic disease. On Day 3, supernatants from whole spleen cells of adjuvant-injected rats did not exhibit abnormal LAF activity. By Day 10, LAF activity in splenic supernatants from arthritics was significantly (P less than or equal to 0.05) higher than normal, although the increase was no greater than 60%. On Day 17 the LAF activity from arthritic rats had increased an average 300% compared to normals. In contrast to the time course of IL-1 activity, Fn and CRP levels in the arthritic rat were significantly higher than normal at all three time points, although there was a transient fall in Fn and CRP concentrations on Day 10. Plasma albumin levels in arthritic rats were subnormal (P less than or equal to 0.01) on Days 3, 10, and 17, although the concentration of plasma albumin on Day 10 was significantly higher than that measured on Day 3. The acute, intermediate, and systemic phases of adjuvant arthritic paw inflammation paralleled the abnormal profile of Fn, CRP, and albumin concentrations over time. However, LAF activity from arthritic rat spleen cells increased gradually and more closely coincided with the systemic appearance of the disease. Since the appearance of abnormal plasma protein levels in arthritic rats preceded the appearance of increased splenic LAF activity, it appears that there is no causal relationship between enhanced splenic LAF activity and early alteration of plasma Fn, CRP, and albumin levels.

The purpose of the paper was to determine whether two clinically active antirheumatic compounds, cyclosporin-A (CS-A) and methotrexate (MTX) were efficacious in the treatment of adjuvant arthritis (AA) in rats, as measured by reduction of paw inflammation, lymphocyte activating factor (LAF) activity and the acute phase response. Parameters of the acute phase response consisted of plasma fibronectin (Fn), C-reactive protein (CRP), albumin and iron. Rats injected with Freund's complete adjuvant on day 1, developed systemic arthritis, which was quantitated by measuring non-injected paw swelling on day 17. When compared to normal animals, AA rats had significantly (P less than or equal to 0.01) increased: (1) splenic LAF activity (100% increase), (2) plasma Fn (58%), and (3) CRP (122%), as well as abnormally reduced levels of: (1) plasma albumin (53% reduction), and (2) iron (54%). Orally dosing AA rats from days 3 to 17 with the immunoregulatory drugs, CS-A (3 and 5 mg/kg) or MTX (0.5 and 1 mg/kg), significantly (P less than or equal to 0.01) reduced paw inflammation (100% reduction), increased final body wt 40-50 g over arthritic controls and decreased LAF activity from splenic leukocytes. The acute phase response, often associated with a high degree of LAF activity, was significantly (P less than or equal to 0.01) decreased by dosing with CS-A (3 and 5 mg/kg) and MTX (0.5 and 1 mg/kg). The inhibition of the acute phase response was measured by reduction of high plasma Fn levels (42-79% decrease) and CRP levels (57-100% decrease) as well as elevation of subnormal levels of plasma albumin (57-101% increase) and iron (40-114% increase). Dosing with the nonsteroidal anti-inflammatory drugs (NSAIDs), aspirin (50 and 100 mg/kg) or phenylbutazone (10 and 30 mg/kg), significantly inhibited paw inflammation (29-85%), but did not decrease the high rate of splenic LAF activity, nor did aspirin (55, 100 and 200 mg/kg) or phenylbutazone (1, 10 and 30 mg/kg) alter the acute phase response in AA rats, as measured by levels of plasma Fn, CRP, albumin and iron. Since CS-A and MTX have been reported to be effective in the treatment of RA, their activity in the LAF, Fn, CRP, albumin and iron assays of the AA rat suggests that these immunological and serological parameters may be useful in identifying potential antirheumatic drugs and distinguishing them from standard NSAIDs.

In vivo studies with normal and adjuvant-induced arthritic rats were undertaken in order to measure the effects of glucocorticoids on paw inflammation and plasma fibronectin (Fn) levels. Dexamethasone, methylprednisolone, and corticosterone all enhanced plasma Fn levels in normal animals. All drugs also significantly decreased inflammation in arthritic rats as measured by paw swelling. Of the three glucocorticoids, only corticosterone did not significantly enhance Fn levels in arthritic rats, possibly due to its lesser potency and narrow therapeutic window.

Rats with adjuvant-induced arthritis (AA) were used to determine whether chronic systemic paw inflammation was accompanied by appearance of the acute phase response, an increase in splenic interleukin-1 (IL-1) production, and a reduction of nonhelper T cells in the spleen and peripheral blood. Two weeks after injection of adjuvant, the rats developed significant (P less than or equal to 0.01) swelling of the noninjected paw indicative of systemic inflammation. The rats with AA also exhibited signs of the acute phase response, as measured by a significant increase in plasma C-reactive protein (138% above normal) and a significant decrease in plasma albumin (47% below normal), zinc (30% below normal), and iron (58% below normal). IL-1 production from spleen cells of rats with AA was increased 115% compared with normals. Results from immunofluorescence studies with W3/25 and OX8 antibodies to distinguish rat T-helper-inducer (TH) spleen cells from suppressor-cytotoxic (nonhelper T) spleen cells indicated no significant difference between the percentage of OX8+ cells in spleens of arthritic rats compared with OX8+ cells in spleens of normal rats. The W3/25+-to-OX8+ ratio of 1.6 +/- 0.2 for normal rat spleen cells (33% to 21%) was not significantly different from the arthritic rat ratio of 1.9 +/- 0.1 (36% to 19%). When the phenotypes of peripheral blood mononuclear cells were analyzed, the normal animals possessed a greater percentage of W3/25+(TH) cells than did rats with AA. Normal blood mononuclear cell samples were composed of 51% +/- 3% W3/25+ cells and 22% +/- 2% OX8+ cells, and the samples from rats with AA contained 43% +/- 4% W3/25+ cells and 24% +/- 3% OX8+ cells. Thus, the helper-to-nonhelper ratio was higher for normal rats (2.3 +/- 0.1) than for arthritic rats (1.8 +/- 0.2). The data indicated that the appearance of the acute phase response and the abnormally high rate of splenic IL-1 production in the rats with AA did not stem from a subnormal percentage of OX8+ nonhelper T cells in the spleen or peripheral blood.

Auranofin, a member of a class of compounds with disease modifying activity, was given to arthritic rats to determine if it could reverse the abnormal plasma concentrations of fibronectin (Fn), C reactive protein (CRP), and albumin, which were unaffected by treatment with non-steroidal anti-inflammatory drugs (NSAIDs). When auranofin was orally administered for two weeks to adjuvant induced arthritic rats it significantly inhibited swelling of the injected and non-injected paws at doses of 3 and 10 mg/kg. Rocket electroimmunoassay measurement of plasma proteins in normal, arthritic, and auranofin treated arthritic rats indicated that auranofin at 10 mg/kg significantly decreased (by 77%) the abnormally high concentration of arthritic rat plasma Fn, though it had no effect on Fn concentrations when administered to normal rats. CRP, which was raised approximately twofold above normal in arthritic rats, was reduced by 56% after treatment of arthritic rats with auranofin at 10 mg/kg, though CRP concentrations in normal rats were unaffected by auranofin treatment. Depressed albumin concentrations in arthritic rats were significantly enhanced (by 30%) by dosing with 10 mg/kg of auranofin. At the 3 mg/kg dose, auranofin did not significantly change plasma concentrations of Fn, CRP, and albumin in arthritic rats. At a dose of 10 mg/kg, however, auranofin, in addition to inhibiting chronic systemic paw inflammation, also altered abnormal concentrations of plasma Fn, CRP, and albumin in the adjuvant arthritic rat, thus distinguishing auranofin from standard NSAIDs we have previously tested.